The goal of this research is to improve healthcare and coordination of care among children in homeless families, which will lead to improving health outcomes in this vulnerable population. To achieve this goal, the proposed study will examine whether and how homelessness influences healthcare use of children. The main research aims are to examine 1) whether children's health service use changes before, during and after their initial homeless episode and 2) whether children who become homeless differ from other low-income housed children in their healthcare use before their first homeless episode, afterwards, and whether there are differences in the change in use around the homeless episode relative to housed children. The proposed study will use a retrospective cohort design based on a longitudinal archive of administrative data. The longitudinal design of this study will allow for the investigation of temporal patterns of service use, which will provide insight into the impact of homelessness on health service utilization among children. This study will have the added benefit of comparing children in homeless families with low-income housed children. The proposed research design will provide information on the healthcare use of children before, during, after their episodes of homelessness, as well as a comparison group of low-income housed children. Results from this study will help identify a group of children with a great need for healthcare, which will enable healthcare and homeless service providers to use their limited resources for those who need timely, comprehensive, and integrated health services. The findings of this study will provide information on services to improve healthcare use for homeless children and to strengthen the coordination of healthcare and homeless services. In addition, the findings will allow us to make more targeted and efficient sampling decisions for future studies.